Filter for aquarium apparatus

Abstract: A filter for an aquarium apparatus includes a filter tank casing (13B), a filter unit accommodated in the filter tank casing for filtering water from a tank (1) and returning filtered water thereto, a water pool section (31p) for collecting water from the tank and supplying water overflowing therefrom directly to a filter material (33) of the filter unit. The filter unit physically and biologically filters water from the tank and returns filtered water thereto.

Description: This invention relates to a filter for an aquarium apparatus for keeping and displaying tropical fish or the like. An aquarium apparatus consists of a tank, a lid, an illuminator, a filter, etc. Of these components, the filter serves to physically and biologically filter out contaminants from the water contained in the tank. The filter and illuminator are designed to constitute a lid covering the open top of the tank. In the filter, water pumped from the tank with a pump mechanism is showered from a shower pipe or a trough onto a filter material provided in a filter unit accommodated in a filter tank casing. The filter unit is configured to concurrently perform physical filtering for filtering out floating particles in the water using chemical fibers or other such filter material and biological filtering for filtering out organic substances dissolved in the water using bacteria living in a filter material such as gravel. In the prior art filter for the aquarium apparatus, water is supplied to a filter unit by showering. This has the advantage of increasing the amount of dissolved oxygen available to the fish or the like in the aquarium tank. However, showering also has the effect of reducing the amount of dissolved carbon dioxide available to aquatic plants in the aquarium tank. This method of supplying water is therefore inappropriate for the filter of an aquarium apparatus used mainly to display aquatic plants. It is desirable to preclude the above inconvenience by providing a filter for an aquarium apparatus which can be used irrespective of whether the apparatus is used to display fish or aquatic plants. US 5 108 594 discloses an aquarium trickle filter for filtering aquarium water. The filter includes a removable drip tray which covers a chamber containing filter material and which has grooves for uniformly dispersing incoming water over the filter material. Some showering effect is likely to occur as water leaves the drip tray although this will not be great due to the configuration of the drip tray. An object of the present invention is to alleviate at least some of the problems of the prior art. According to the present invention, there is provided a filter for an aquarium apparatus, adapted to filter with a filter material water pumped from a tank with a pump and return the filtered water into the tank, comprising a filter casing that accommodates the filter material therein and has an upstream side water pooling section for collecting water pumped from the tank and downstream side water discharge ports, and a trough detachably attached to the filter casing, characterised in that the trough is provided with a plurality of pairs of upstream side projections and downstream side holes or pairs of downstream side projections and upstream side holes for supplying water from the water pooling section to the filter material provided inside the filter casing. In the case of the filter for an aquarium apparatus used mainly to display the fish or the like, it is advantageous to supply water overflowing from the water pool section to the filter material via the trough because this produces a showering effect to enable the dissolved oxygen content in water to be increased. In the case of the filter for an aquarium apparatus used mainly to display aquatic plants or the like, however, water from the water pool section is supplied directly to the filter material without using the trough so as not to produce a showering effect that reduces the dissolved carbon dioxide content in water. A preferred embodiment of the present invention will be described by way of example only with reference to the accompanying drawings in which:- Figure 1 is a perspective view showing an aquarium apparatus incorporating an embodiment of the filter for an aquarium apparatus according to the invention; Figure 2 is a sectional view taken along line II-II in Figure 1; Figure 3 is a plan view showing a first filter subunit with its lid removed; Figure 4 is an exploded perspective view showing essential elements of the first filter subunit; and Figure 5 is an explanatory view showing how water is returned from a filter tank casing. An embodiment of the invention will now be described with reference to Figure 1 to Figure 5. Figure 1 is a perspective view showing an aquarium apparatus incorporating an embodiment of the filter for an aquarium apparatus according to the invention. Referring to Figure 1, reference numeral 1 designates a tank open at the top, and 11 designates a lid covering the open top of the tank 1. The lid 11 includes an illuminator 12A equipped on its underside with fluorescent lamps for illuminating the tank 1 and a filter 12B for filtering the water in the tank 1. The illuminator 12A is disposed so as to cover the front part of the top of the tank 1, while the filter 12B is disposed to cover the rear part of the top of the tank 1. The filter 12B comprises a filter tank casing 13B set atop the tank 1, a lid 13C covering the open top of the filter tank casing 13B, a pump mechanism 20 accommodated in part of the filter tank casing 13B, a first filter subunit 30 occupying most of the filter tank casing 13B, and a second filter subunit 40 disposed in the tank 1 and connected to the first filter subunit 30. An engagement member 14 is provided on the underside of the rear portion of the filter tank casing 13B. The engagement member 14 extends downward in an L-shaped sectional profile and supports a second filter casing 41 which is part of the second filter subunit 40. The pump mechanism 20 includes a motor 21 accommodated in the filter tank casing 13B, a first cylindrical member 22 extending from a motor 21 into the tank 1, an intermediate frame 23 provided at the lower end of the first cylindrical member 22 and accommodating a vane (not shown), a second cylindrical member 24 extending downward from the intermediate frame 23, a strainer 25 mounted on the lower end of the second cylindrical member 24, and a delivery pipe 26 extending from the intermediate frame 23 into the filter tank casing 13B and having a U-shaped end portion. The first filter subunit 30 includes a first filter casing 31 with a partitioning wall 31w defining a water pool section 31p for collecting water from the delivery pipe 26, a bottom member 32 placed on the bottom of the first filter casing 31, a first filter material 33 for physical filtering accommodated in a space defined by a vertical portion 32h of the bottom member 32 and the partitioning wall 31w, and a trough 34 having one end engaged with the partitioning wall 31w and the other end supported by support pins 32p projecting from the bottom member 32. The bottom of the first filter casing 31 has discharge ports 31ha and 31hb, and the bottom of the bottom member 32 has a plurality of thin slits 32s. A flow path is therefore formed between the two components when the bottom member 32 is placed on the bottom of the first filter casing 31. The trough 34 is supported to be higher on the side of the partitioning wall 31w and lower on the side of the support pins 32p so that water will flow along the trough 34 from the side of the partitioning wall 31w to the side of the support pins 32p. The bottom of the trough 34 is flat and has a large number of projection-hole sets each consisting of a projection 34i and a hole: 34h. In each set, the projection 34i is on the upstream side and the hole 34h is formed adjacent the downstream side of the projection 34i and has the same width as the projection 34i. Water overflowing from the water pool: section 31p passes through the holes 34h to the first filter material 33. Floats 35A and 35B are disposed opposite the discharge ports 31ha and 31hb, and a drain pipe 36 is, connected to the discharge port 31ha. Water is returned through the drain pipe 36 into the tank 1. The second filter subunit 40 includes the second filter casing 41 shaped like an openable and closable box and a plurality of buckets 42 accommodating a plurality of second filter materials such that these materials will not be mixed. The second filter casing 41 is provided at its top with an inverted L-shaped engagement piece 41f and is detachably supported on the first filter casing 31 by engagement of the engagement piece 41f with the L-shaped engagement member 14 depending vertically from the bottom surface of the filter tank casing 13B. An inlet provided at the top of the second filter casing 41 communicates with the discharge port 31hb via a connecting pipe 43. Water from the discharge port 31hb once flows down to the lower end of the second filter casing 41 and then rises. As it rises, it filters through the second filter materials accommodated as biological filtering materials in the buckets 42 before being returned to the tank 1 through a discharge port 41h provided in the top front of the bucket. The filtering operation will now be described. When the motor 21 is operated, water is drawn through the strainer 25 and supplied through the second cylindrical member 24, the intermediate frame 23 and the delivery pipe 26 to the water pool section 31p. Water overflowing from the water pool section 31p flows along the trough 34. At this time, large particles which are caught and removed by the projections 34i. The water removed of large particles is supplied in a showering fashion from the holes 34h onto the first filter material 33. When water is supplied in this way, it dissolves oxygen owing to the showering effect. Thus, the dissolved oxygen content is increased. The water that has been physically filtered through the first filter material 33, is collected in the first filter casing 31 and 70 to 80% of it is returned through the discharge port 31ha and the drain pipe 36 to the tank 1, while 20 to 30% of it is supplied through the discharge port 31hb and the drain pipe 43 into the second filter casing 41. The water thus supplied to the second filter casing 4 is biologically filtered through the second filter materials in the buckets 42 and then returned through the discharge port 41h to the tank 1. The amount of water supplied to the second filter casing 41 is limited to 20 to 30% so that the biological filtering can proceed slowly and effectively and also so that the overall size and thickness of the second filter casing 41 can be reduced so as to secure a large space for keeping fish and/or plants in the tank 1. As shown above, in this embodiment of the invention water is first filtered physically in the first filter subunit 30 and then filtered biologically in the second filter subunit 40. Thus, even when the first filter material in the first filter subunit 30 clogs and is removed for replacement, the second filter subunit 40 continues to function, so that satisfactory water quality can be maintained by biological filtering through the second filter subunit. Further, since the second filter susbunit 40 is disposed in the tank 1, it will not wet the area surrounding the aquarium apparatus. Further, since the floats 35A and 35B are disposed to cover the discharge ports 31ha and 31hb, the gurgling sound produced by water flowing down through the discharge ports 31ha and 31hb can be muffled. While the above embodiments relate to the case in which the projections 34i are provided on the upstream side and the holes 34b on the downstream side, the projections 34i may be provided on the downstream side and the hole 34h on the upstream side. This arrangement can produce substantially the same effect. Further, while it was described that a part of the water is returned from the first filter subunit 30 to the tank 1, insofar as sufficient biological filtering in the second filter subunit can be ensured it is instead possible to use an arrangement in which all of the water in the first filter subunit is supplied to the second filter subunit. Further, while the filter unit was described as being divided into the first and second filter subunits 30 and 40, it is possible to accommodate both the first and second filter subunits in the filter tank casing. As has been described in the foregoing, according to the invention the filter tank casing is provided with the water pool section from which overflow water is supplied to the filter unit or the first filter subunit thereof either directly or by showering from a trough. In the case of not using any trough, the dissolved carbon dioxide content is not reduced, and thus the structure may be employed as a filter for an aquarium apparatus mainly for displaying aquatic plants. In the case of using the trough, on the other hand, the dissolved oxygen content can be increased, and thus the structure can be employed as a filter for an aquarium apparatus mainly for displaying fish.

Claims: A filter for an aquarium apparatus, adapted to filter with a filter material (33) water pumped from a tank (1) with a pump (20) and return the filtered water into the tank, comprising a filter casing (13B) that accommodates the filter material (33) therein and has an upstream side water pooling section (31p) for collecting water pumped from the tank and downstream side water discharge ports (31ha, 31hb), and a trough (34) detachably attached to the filter casing (31), characterised in that the trough (34) is provided with a plurality of pairs of upstream side projections (34i) and downstream side holes (34h) or pairs of downstream side projections (34i) and upstream side holes (34h) for supplying water from the water pooling section (31p) to the filter material (33) provided inside the filter casing (31).

Inventors: KIKUTA TOSHIKI, KIKUTA, TOSHIKI, KIKUTA, TOSHIKI, C/O NISSO INDUSTRY CO., LTD.
Applicants: NISSO IND CO LTD, NISSO INDUSTRY CO., LTD.
Application year: 1994
Main classification: A01K63
IPC codes: A01K63